ARDMS SPI STUDY GUIDE FINAL REVIEW EXAM AND ANSWERS 2024
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Course
ARDMS SPI
Institution
ARDMS SPI
In soft tissue, if the frequency of a wave is increased the Propagation Speed (PS) will... - Answer Remain the Same because stiffness and density affect Propagation Speed.
What is the audible range? - Answer 20-20,000Hz
>20,000Hz=Ultrasound
Frequency is measured in - Answer Hertz ...
ARDMS SPI STUDY GUIDE FINAL REVIEW EXAM AND ANSWERS 2024.
In soft tissue, if the frequency of a wave is increased the Propagation Speed (PS) will... - Answer Remain the Same because stiffness and density affect Propagation Speed.
What is the audible range? - Answer 20-20,000Hz
>20,000Hz=Ultrasound
Frequency is measured in - Answer Hertz (Hz)
is Cycles per Second
Not affected by sonographer Increase Frequency; Decrease Depth or axial focus
A period is the length of time it takes for - Answer one complete wavelength to pass a fixed point
indirectly related to frequency Pd=1/Frequency
PRP is determined by - Answer Transmit time and receive time.
Period is measured in - Answer Time (μs)
When the sonographer changes the imaging depth what parameters are changed? - Answer PRP , PRF, Duty Factor are all affected by changing imaging depth.
What is duty factor? - Answer the percentage or fraction of time that the system transmits a pulse or is producing sound
UNIT: % PERCENTAGE DF=PD/PRP
PRP is inversely related to PRF, So an increase in PRF would lead to an increase in DF because PRF and DF
are directly related
The actual time from the start of a pulse to the end of that pulse.
Propagation Speed in SOFT TISSUE - Answer 1.54 mm/μs
(1540 m/sec)
Unit of measurement for Pulse Duration, Duty Factor, PRP , and Period - Answer Time, (μs)
Pulse duration is determined by - Answer The Sound Source only, not by the medium through which the
sound travels. Pulse Duration is the time it takes for one pulse to occur.
Pulse Duration is controlled by - Answer the ultrasound system and transducer
The ultrasound system and transducer allocate the Frequency, which is inversely relates to time as a reciprocal. So, if the PRF goes up, then the PRP goes down due to an increase of vibrations causing shorter Wavelengths, which cause shorter Pulse Durations.
HIGHER PRF- SHORTER PRP LOWER PRF- Longer PRP
Pulse Duration Formula - Answer pulse duration (μs) = # cycles in pulse/frequency(MHz)
PD= Number of cycles in Pulse/ Frequency(Hz)
or PD= Number of cycles in Pules x Period (T)
Spatial Pulse Length (SPL) (measurement) - Answer The distance that a pulse occupies in space from the
start to the end of a pulse. (mm)
Typical values for spatial pulse length in soft tissue. - Answer 0.1 to 1.0 mm
SPL= 0.1 - 1.0mm
Spatial pulse length is determined by - Answer sound source and medium
Frequency and Stiffness/Density of tissue will determine the Spatial Pulse Length. Low PRF in normal soft tissue yields a longer spatial pulse length.
Higher PRF in normal soft tissue yields a shorter spatial pulse length.
Spatial Pulse Length is directly proportional to - Answer The Number of Cycles in the Pulse
and The Wavelength (Directly Proportional means that increased SPL will increase both the number of cycles in the pulse and the wavelength if increased).
Spatial pulse length is inversely proportional to - Answer Frequency (MHz)
(Inversely Proportional means that increased SPL will lower frequency. This is because axial resolution is better with lower frequency)
SPL=1/F
If frequency goes down, SPL gets longer.
[Think, LOW Hz= LONG WAVES]
If frequency goes up, SPL gets shorter.
[Think, High Hz= SHORT WAVES]
Pulse Duration (PD) - Answer The actual time from the start of a pulse to the end of that pulse; a single transmit, talking, or "on" time. Time the pulse is on typically measured in (ms).
Pulse Length - Answer The distance of the pulse start to end or the
duration or length of a single pulse Pulse Length is typically measured in (mm).
the ability of an object to resist compression and relates to the hardness of a medium? - Answer Stiffness. Think:
↑ Stiffness ↑ Speed
↓ Density ↑ Speed
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